LONDON — Police officers from 40 departments in England and Wales are returning to their home assignments three months after they stepped in to help local authorities respond to the nerve agent attack on a Russian ex-spy.

The Wiltshire Police force, which serves the English city of Salisbury, reported Monday that it has spent about 7.5 million pounds ($10 million) dealing with the aftermath of the March 4 attack on Sergei Skripal and his daughter, Yulia.

Chief Constable Angus Macpherson says his department wouldn't have been able to handle the crisis without the 1,230 outside officers who staffed cordons throughout the city.

Macpherson says the officers no longer are needed because some decontaminated sites are being turned over to their owners and private security guards are being stationed at the remaining locations.